Automatic stoker



y A. V.,SAMPSEI I 2,164,350

AUTOMATIC STOKER Filed Mafch so, 1931 1/7. vfiwm llsel,

PM! July '4, 1939 A QUNITEI) STATES PATENT orrlca 2.10am f AUTOMATIC s'roxaa I Arthur v. Sampsel, Lafayette, Ind., assignor to Sears, Roebuck & Company, Chicago, Ill., a corporation of Delaware Application March so, 1931, semi No. 520,502

I 4 Claims. My invention relates to controls for automatic stokers for feeding fuel such as coal, to furnaces.v

. .Another object of the invention is to, provide means regulating the length of time-of each periodical actuation of the stoker.

These and other objects are attained by the means described in the specification and illustrated in the drawing in which;

Fig. 1 is a diagrammatic view including the electric power circuit and the controls for opening and closing said circuit through the motor which drives the apparatus;

Fig.. 2 is a front view of the time interval or fire-kindler control mechanism with .the cover.

removed; and

Fig. 3 is a side view of said mechanism with the cover shown in dotted lines.

As shown diagrammatically in Fig. 1, a motor 32 has a shaft IIII with a worm I02 which turns a worm wheel I03 with which an eccentric 104 rotates. The eccentric reciprocates a rod IIII guided by the pin-and-slot connection at I I5, I It, said rod operating through its arm IIfla, a link I20, bel1 crank lever arms I2I and I22 and pivoted pawl I23 to intermittently rotate a ratchet wheel I24 with which a conveyor worm or screw 69 turns. The conveyor receives fuel from a hopper 60 and feeds it along a conduit 68 to a burner 43. The angle through which the ratchet wheel is moved by the pawl I23 may be governed by a guard I30'connected by an arm I33 and a link I34 to a knob or dial I35 bearing a scale in juxtaposition to a stationary pointer I36. Any other drive may be employed, since the invention concerns the control of the motor.

In accordance with my invention, a conductor I40 leads from a suitable source of electricity to one terminal of the motor. A conductor I from such source leads from the other terminal to themotor to a binding post I42 of a time-interval-- switch, presently to be described, and includes a normally closed thermostatic safety switch I43 adapted to operate, in the event of excessive or dangerous heat-such as might be du'e to failure of the room thermostat switch, or the interval contactor switch, to open the motor circuit at the proper time-to automatically open the motor circuit at a point where the other switches cannot complete the motor circuit and energize the motor to feed more fuel to the fire. Conductor I44 leads to another binding post I45 of the timeinterval switch. Conductor I46 bridges across conductors I and] I44 and includes a normally open thermostatically controlled switch I", of well known construction, adapted to be located 'at some central point in a building or residence. such as the main hallway, or living room, and to be set'or adjusted so as to close when the tem-' ,15 peraturefalls below-a certain predetermined del gree and to open when the temperature reaches said predetermined degree, the electric motor being operated during the interval to actuate the stoker and feed coal to the fire. A time interval switch is connected in circuit between said terminalsl42 and I45, and acts to close the circuit through the motor to feed fuel to the fire at regularly recurring intervals, in the manner presently described, thereby to keep the fire kindied or alive.

Irrespectiveof the action of the aforesaid thermostatic switch I41, in its control of the operation of the motor to feed fuel to the fire in response to fall of the temperature in the room or space ularly recurring predetermined intervals of time, 5 1

to effect what may be termed fire kindler control", or time interval control, of the feeding of fuel; that is, thedelivery to the fire at fixed time intervals of a small quantity of fuel sufilcient to keep the fire kindled or burning, thus insuring the constant maintenance of what may be termed a "pilot fire", This i s necessary where there may bea relatively long interval between feedings of fuel to the fire in response to operations of the thermostatic switch I41, with consequent danger of the fire going out between operations. Such danger occurs particularly during periods of mild weather, when the room temper ature may not, for a considerable stretch of time, reach the degree" required to bring the thermo- 50 static switch I41 into operation. I The fire-kindler control switch mechanism is shown diagrammatically in, Fig. 1,- but is illustrated more in detail in Figs. 2 and3. I50 isa base plate of fibrous or other non-conducting maunder a guide bar I55, the latter being secured at its opposite ends to base I55 by screws, but between said ends, where it passes over plate I53, being spaced away from said base. At the upper narrow end of plate I53, a part out therefrom forms a pointer I55, beyond which said plate extends forward and downward to constitute an overhanging arm I51. The position of pointer I55 in reference to a graduated scale on base I55 indicates the angular position to which plate I53 is adjusted or tilted on its pivot stud I54. To

secure plate I53 in the desired angular position,

it is engaged by a winged clamp-nut I58 on' a fixed screw stud which projects through a curved slot I59 in plate I53, the arc of curvature of said slot being concentric with pivot stud I54. By loosening nut I53 the plate I53 can be turned on its pivot stud I54 a distance limited by slot I59.

I50 is a clock mechanism, or the equivalent thereof, secured to the lower end of plate I53 and having a projecting shaft I5 I, revolving preferably once each hour, and having secured thereto a cam I52 engaged by the lower free end of an arm I53, which is rigidly secured at its upper end to a yoke I54, pivoted by a bolt I55 to the extremity of the arm I51 of plate I53.

I55 is a mercury tube switch, of the type of the well known Mercoid switch of the American Radiator 00., secured in the yoke or clamp I54, and comprising a sealed glass tube containing a quantity of mercury I51 and two electric terminals I58 and I59, from which terminals conductors lead through the wall of the glass tube to the binding posts I45 and I42, respectively.

Assuming that the cam I52 rotates once an hour, it will be apparent that by its action on arm I53, said cam will tilt the tube to the right and cause the mercury to run to that end of the tube and there electrically connect terminals I59 and I59 in the manner indicated in Fig. 1. Further, it will be apparent that this will occur once each hour, thereby closing the motor circuit between the binding posts I42 and I45 and causing the motor to actuate the fuel feed-screw so long as the mercury remains in said position to connect the tube terminals I58 and I59. But how long the mercury will remain in said position, and consequently the duration of each closing of the motor circuit and its actuation of the fuel-feed screw, is determined by the position in which the plate I53 is held by.c1amp-nut I58 and may be varied by changing the angular position or tilt of said plate.

The high point of cam I52 passes from under the end of arm I53 at the same instant each hour, and simultaneously therewith the tube tilts to the left and the mercury flows to that end of the tube and opens the circuit at the terminals within the tube. On the other hand, the in stant at which the tube is tilted to the right sufficiently to cause the mercury to run to that end of the tube and electrically connect the terminals, may be advanced or retarded according to the position of plate I53.

In practice, the duration of contact is preferably variable from a maximum of say twelve minutes to'a minimum of say thirty seconds. The length of slot I59 may be such as to permit of that or any other desired range of duration. For example, when plate I53 is swung as far to the left as slot I59 permits, contact arm I53 does not tilt the mercury tube I55 sufliciently to cause the mercury therein to close the circuit until the contacting end of said arm has nearly reached the highest point of cam I52 and is about to drop 'to the lowest point thereof. Hence the closingof the circuit will be of very brief duration, say half a minute. But by swinging the plate I53 to the right, the pivotally supported mercury tube is brought to a position more nearly level, and consequently cam I52 will tilt it into contact-making position a considerable time-say twelve minutesbefore the end of arm I53 drops of! the highest point of said cam.

If said plate is set to the limit of its adjustment toward the left, the shifting of the mercury to the right-hand end of the tube will be retarded to the limit, and the duration of its closing of the motor circuit correspondingly curtailed to the minimum, say of thirty seconds. Setting of the plate I53 to the limit of its adjustment toward the right will have the reverse efiect, and will result in increasing the duration of closing of the motor circuit to the maximum, say of twelve minutes.

The provisions thus made for changing or adjusting the duration, say within a range of onehalf a minute to twelve minutes, of each actuation of the fuel conveyor for purposes of kindling the fire, as well as the means whereby such variation may be accompilshed, are particularly important features of this invention. Thereby the apparatus is made adaptable to a wide range of variable conditions of use; for'example, from conditions under which feeding of coal for onehalf minute once each hour may suflice to keep the fire kindled, to conditions under which feeding of the coal for twelve minutes once each hour may be required for that purpose.

The automatic operation of the stoker in response to the two controls, or dual-controls, will be readily understood from the preceding description. vrIhe room thermostat switch M? and the mercury fire-kindler switch 555 are connected in parallel between conductors MI and HM. If the lire, as kept kindled and burning by the fuel fed thereto periodically by the closing of said mercury switch I55, does not sufllciently heat the room or space in which said thermostatic switch I41 is located, then the latter closes and causes fuel to be fed to the fire until the temperature of the room reaches the predetermined minimum and opens said thermostatic switch. It may happen that while either the switch i41 or the switch I55 is closed, the other will be closed also; and

that after one switch has opened its part of the circuit, the other switch will continue to maintain its parallel part of the circuit in a closed condition and thus continue the feeding of fuel to the fire.

The determination of the proper setting of the adjustments of both the transmission gearing and the fire-kindler control switchwill of course de- 2,164,850 be determined would be that of the ratchet drive of the transmission, gearing, which adjustment cold weather. 1

is effected by turning the knob or dial I35 of Fig. 1. Assuming this adjustment to be set so that-each forward movement of the pawl I23 will rotate the ratchet wheel I24 (and with it the fuel feed-screw) a distance of two teeth of said wheel when the room thermostat switch closes the circuit, the fuel feed-screw is rotated the distance of two teeth of the ratchet-wheel for each forward movement of the pawl, and continues such operation until the room temperature rises to the predetermined minimum and actuates the thermostatic switch to open the circuit. This adjustment should be such that the rotation imparted to the fuel feed-screw will deliver sufilcient fuel to the fire to result in increasing the room temperature to the predetermined minimum degree within a reasonable time, say from three minutes for mild weather to fifteen minutes for -Assuming an installation using the same coal for a relatively large house, or say twelve rooms,

the adjustment would be set to rotate the ratchet wheel (and fuel feed-screw) a larger number of teeth, say five, for each forward movementof the pawl, thus to deliver a correspondingly larger I quantity of coal in response to closing ofthe motor circuit by' the room thermostat switch and enable the predetermined degree of temperature to be reached within a reasonable time, say from three minutes for mild weather to fifteen minutes for cold weather.

Assuming similar installations, but using coal having a relatively lower B. t. u. content, if the same adjustments were used as described above, relatively longer periods of operation would be necessary before the room temperature would reach the degree to cause the thermostat switch to open the motor circuit. shortened by setting the adjustment to rotate the ratchet wheel (and fuel feed-screw) a larger number of teeth on each forward movement of the pawl. I

This adjustment only takes into consideration the size of the house to be heated and the character of the fuel being burned and is determined without regard to the adjustment of the fire kindler control next described.

As thus appears, the transmission gearing herein described affords a flexibility of adjustment to meet the particular conditions encountered in making different installations, including different sizes of residences, apartments, or other buildings, and different kinds of fuel.

Coming now to the adjustment of the fire kindler control switch-assume an installation to be made in a small house, say of five rooms, using relatively slow burning coal-the adjustment would be such as to give a relatively long duration, say five minutes, of closing of the motor circuit and operation of the fuel feed-screw once each hour; in other words, a relatively small quantity of the slowburning coal would bedelivered once each hour. If the coal used were fast burning the; adjustment would be such as to increase said duration of operation of the This time would be,

the fire kindler control must beset accordingly. For example, assume the ratchet mechanism to be adjusted to feed two teeth for each forward stroke of the pawl for afive room house, then for-a larger house, say of twelve rooms, with the ratchet mechanism adjusted to feed flveteeth for each forward stroke of the pawl, the adjustment of the fire kindler control switch would be such as to shorten the duration of the closing of the motor circuit once each hour. As thus appears, the adjustment of the fire kindler control switch must take into consideration the adjustment of the ratchet mechanism of the transmission gearing.

Differences in into consideration in setting the adjustment of the duration of the closing-of the'motor circuit,

' house than for a small house, the adjustment of '15 fiue drafts should also be taken longer duration, with correspondingly larger amount of coal, being required with a strong stack draft than with a weaker stack draft.

' As thus appears, there is a wide range of flexibility of adjustment of the fire kindler control switch, suflicient to efiiciently care for practically any and all variations of conditions encountered in making different installations, Furthermore, as clearly appears, the first kindler control switch or mechanism herein described can be adjusted on the job; that is to say, the mechanism as manufactured can be installed in any house or building, and can there be adjusted to meet the particular conditionsencountered; It can also be shifted from one installation to another and adjusted to the particular conditions of the new installation.

What is claimed is:

1. In combination, a furnace, a mechanicalv stoker, a single control circuit controlling the operation of the stoker, a furnace thermostat and a room thermostat in series with the control circuit, and'a time switch connected-in multiple solely with the room thermostat.

' 2. In combination, a furnace, a motor operated stoker, time control means for periodically closing the motor circuit, a furnace thermostat and a room thermostat operable to close the motor circuit independently of the time control means,

said time control means being adapted to closev and open the motor circuit when the furnace thermostat is in circuit closing position and the room thermostat is in circuit opening position.

3. In combination, a furnace, a motonoperated stoker, time control means for periodically closing the motor circuit, a furnace thermostat and a room thermostat operable to close the motor circuit independently of the time control means,

said time control means being adapted to,'close and open the motor circuit when the furnace thermostat is in circuit closing position and the room thermostat is in circuit opening position, together with means associated with said time control means for varying the duration of closure of the motor circuit independently of periodicity.

4. In combination, a furnace, a motor driven stoker, a single control circuit for starting and stopping the motor, a furnace switch responsive to temperature conditions in the furnace, a room switch responsive to temperature conditions in a room to be heatedjsaid furnace and room switches being connected in series in 'said control circuit,- and a time switch connected ininul- Aa'rirua v. smsan. 9'

CERTIFICATE OF CORRECTION. A Patent No. 2,16b,,350, July L 19 9. ARTHUR v'. SAMP-SEL. I

It is hereby certified that error appears in the printec't specification of the above numcered. patent requiring correction as foliows Page 1, first column, line 51, for the word "to" read of} page 5, second colnmn, line 27, for "first" read fire; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office. v I

Signed and sealed this 5th day of September, A. D. 1959,

Henry Van Arsdale,

(Seal) f Acting Commissioner of Patents. 

